This invention relates to a picture analyzer, and more specifically to a device for detecting a region in a picture which is equivalent in tone to a point which is optionally specified in the picture.
A "VIP21CH" type picture analyzer manufactured by Olympus Kogaku Kogyo Kabushiki Kaisha (Olympus Optical Industry Co., Ltd.) has been proposed in the art, to detect only a region having a tone from a color picture formed with a number of tones. In such a conventional equivalent tone region detecting device, several reference tones are set in advance, and among these tones, a desired one is selected so that a region whose tone is equivalent to the selected tone is detected from the picture. However, since the reference tones are set in advance, the conventional device cannot meet a requirement for detecting a region from a picture, the tone of which is equivalent to any desired one of the tones which are included in the picture.